Mounting structure of oil pump

ABSTRACT

Connecting ports are respectively connected through joint plugs to inlet ports formed on the upper surface of an oil pump. The joint plugs have thin-walled cylindrical portions and circular flange portions formed at axially central positions of the respective cylindrical portions. The inlet ports are tapered in such a manner that the inner diameters of the inlet ports gradually increase toward opening ends thereof. One end portions of the joint plugs are preliminarily press-fitted with the inlet ports until the flange portions abut against the opening ends of the inlet ports, thereby achieving oil tightness. The other end portions of the joint plugs are oil-tightly connected through O-rings to the connecting ports.

CROSS-REFERENCE TO RELATED APPLICATIONS

This nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2005-142482, filed in Japan on May 16, 2005, the entirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mounting structure of an oil pump. More particularly, the present invention relates to a mounting structure of an oil pump, which can make simple and reliable connection of an oil inlet and outlet (inlet port and outlet port) of the oil pump to connected objects.

2. Description of Background Art

Japanese Patent Laid-Open No. 2001-140614 discloses an oil pump for an internal combustion engine that includes a feed pump for supplying oil from an oil tank to various lubricated sections of the engine and a scavenging pump integrated with the feed pump for returning the oil staying at a bottom portion of the engine to the oil tank. The feed pump and the scavenging pump have rotors coaxially mounted on a common drive shaft.

FIG. 5 is a sectional view showing a connecting structure between an inlet port (or outlet port) 71 of an oil pump and a connected object 72 in the background art. As shown in FIG. 5, the inlet port 71 and the connected object 72 are connected with each other through a joint plug 73. An O-ring 75 oil-tightly seals the joint plug 73 and the inlet port 71, and an O-ring 74 oil-tightly seals the connected object 72 and the joint plug 73.

In the background art mentioned above, the joint plug and the two sealing members must be separately prepared when mounting the oil pump to a housing of a lubricated section. Furthermore, it is necessary to prepare any positioning members such as dowel pins for relatively positioning the oil pump and the housing of the lubricated section. As a result, the number of parts and the number of mounting steps become large.

SUMMARY OF THE INVENTION

There is a need for the present invention to provide a mounting structure of an oil pump that can reduce the number of parts and the number of mounting steps required to mount the oil pump to the housing of the lubricated section.

In a mounting structure of an oil pump for sucking lubricating oil from an inlet port and feeding the lubricating oil under pressure from an outlet port, the present invention includes the following aspects.

(1). The mounting structure includes a joint plug for oil-tightly connecting at least one of the inlet port and the outlet port to a connected object. The joint plug has one end portion preliminarily press-fitted with at least one of the inlet port and the outlet port and another end portion adapted to be oil-tightly connected to the connected object by using a sealing member.

(2). The oil pump includes a feed pump and a scavenging pump integrated with each other. The joint plug includes a first joint plug press-fitted with an inlet port of the feed pump and a second joint plug press-fitted with an inlet port of the scavenging pump. The first and second joint plugs having seat surfaces at the same level.

(3). The joint plug has a cylindrical portion and a circular flange portion formed at an axially central position of the cylindrical portion so as to have an outer diameter. One end portion of the joint plug is press-fitted until the flange portion abuts against an opening end of at least one of the inlet port and the outlet port.

According to the present invention, the following effects can be exhibited.

(1). According to the first aspect of the present invention, the joint plug is preliminarily fixed by press-fitting to the inlet port or the outlet port of the oil pump to thereby achieve oil tightness without using any sealing members. Thus, unlike the background art that requires sealing members to mount the oil pump, no sealing members are required. Furthermore, the joint plug is accurately positioned to the inlet or outlet port of the oil pump with no play, thereby exhibiting a positioning function. Accordingly, it is unnecessary to use any positioning members such as dowel pins for accurately positioning the oil pump to the connected object.

(2). According to the second aspect of the present invention, the first and second joint plugs have seat surfaces at the same level. Accordingly, even when the oil pump and the connected object are connected at two positions, the connection therebetween can be easily performed.

(3) According to the third aspect of the present invention, the joint plug is press-fitted into the inlet port or the outlet port of the oil pump until the flange portion abuts against the opening end of the inlet or outlet port. Accordingly, the seat surface of the joint plug can be set at a constant level.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a sectional view of an oil pump along a drive shaft thereof according to an embodiment of the present invention;

FIG. 2 is a view taken in the direction shown by an arrow Z1 in FIG. 1;

FIG. 3 is a view taken in the direction shown by an arrow Z2 in FIG. 1;

FIG. 4 is a sectional view showing a mounting structure of the oil pump; and

FIG. 5 is a sectional view showing a connecting structure between an inlet or outlet port of an oil pump and an internal combustion engine in the background art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings, wherein the same or similar elements will be identified with the same reference numerals.

FIG. 1 is a sectional view taken along the line I-I in FIG. 2. In this preferred embodiment, the oil pump 10 includes a feed pump and a scavenging pump coaxially integrated with each other.

The feed pump of the oil pump 10 includes a feed pump housing 3. The scavenging pump of the oil pump 10 includes a first scavenging pump housing 1 and a second scavenging pump housing 4. An intermediate housing 2 is interposed between the first scavenging pump housing 1 and the feed pump housing 3. The housings 1, 2, 3, and 4 are oil-tightly joined together by using a plurality of screws 11. The drive shaft 5 is rotatably supported to the housings 1, 2, 3, and 4 so as to vertically extend therethrough.

A first scavenging pump rotor 11 is supported to the drive shaft 5 in a pump chamber 11 a of the first scavenging pump housing 1. A feed pump rotor 13 is supported to the drive shaft 5 in a pump chamber 13 a of the feed pump housing 3. A second scavenging pump rotor 14 is supported to the drive shaft 5 in a pump chamber 14 a of the second scavenging pump housing 4.

As shown in FIG. 2, the second scavenging pump housing 4 has two oil outlet ports 21 and 22 opening to the lower surface of the oil pump 10 as viewed in FIG. 1. The outlet port 21 communicates with the pump chamber 13 a of the feed pump to feed the oil through an oil filter (not shown) to a lubricated section. The outlet port 22 communicates with the pump chamber 11 a of the first scavenging pump and the pump chamber 14 a of the second scavenging pump to feed the oil through an oil cooler (not shown) to an oil tank (not shown). A relief valve 20 is provided to relieve a discharge oil pressure of the feed pump to the first scavenging pump when the discharge oil pressure becomes higher than a predetermined value.

As shown in FIG. 3, the first scavenging pump housing 1 has three inlet ports 23, 24, and 25 opening to the upper surface of the oil pump 10. The inlet port 23 communicates with the pump chamber 11 a of the first scavenging pump, and is connected to an oil pan (not shown) of an engine. The inlet port 24 communicates with the pump chamber 13 a of the feed pump, and is connected to the oil tank. The inlet port 25 communicates with the pump chamber 14 a of the second scavenging pump, and is connected to an oil strainer (not shown).

FIG. 4 is a sectional view showing a mounting structure of the oil pump 10. As in the background art, a connecting port 41 that is in communication with the oil filter is connected through a joint plug 51 to the outlet port 21 of the oil pump 10. A connecting port 42 that is in communication with the oil cooler is connected through a joint plug 52 to the outlet port 22 of the oil pump 10. A pair of O-rings 61 oil-tightly seals the outlet port 21, the joint plug 51, and the connecting port 41. A pair of O-rings 62 oil-tightly seals the outlet port 22, the joint plug 52, and the connecting port 42.

In contrast, a connecting port 43 that is in communication with the oil pan is connected through a joint plug 53 to the inlet port 23 of the oil pump 10. A connecting port 44 that is in communication with the oil tank is connected through a joint plug 54 to the inlet port 24 of the oil pump 10. The joint plug 53 has a thin-walled cylindrical portion and a circular flange portion 53 a formed at an axially central position of the cylindrical portion so as to have an outer diameter larger than that of the cylindrical portion. Similarly, the joint plug 54 has a thin-walled cylindrical portion and a circular flange portion 54 a formed at an axially central position of the cylindrical portion so as to have an outer diameter larger than that of the cylindrical portion.

The inlet port 23 is tapered in such a manner that the inner diameter of the inlet port 23 gradually increases toward an opening end of the inlet port 23. Similarly, the inlet port 24 is tapered in such a manner that the inner diameter of the inlet port 24 gradually increases toward an opening end of the inlet port 24. One end portion of the joint plug 53 is preliminarily press-fitted with the inlet port 23 until the flange portion 53 a abuts against the opening end of the inlet port 23, thereby achieving oil tightness. Similarly, one end portion of the joint plug 54 is preliminarily press-fitted with the inlet port 24 until the flange portion 54 a abuts against the opening end of the inlet port 24, thereby achieving oil tightness.

For the purpose of simple connection of the other end portions of the joint plugs 53 and 54 to the respective connecting ports 43 and 44, the seat surfaces of the joint plugs 53 and 54 have the same level, i.e., the upper surfaces of the flange portions 53 a and 54 a of the joint plugs 53 and 54 have the same level. An O-ring 63 is fitted with the other end portion of the joint plug 53 so as to abut against the flange portion 53 a, so that the connecting port 43 is oil-tightly connected to the joint plug 53 by a sealing function achieved by the combination of the flange portion 53 a and the O-ring 63. Similarly, an O-ring 64 is fitted with the other end portion of the joint plug 54 so as to abut against the flange portion 54 a, so that the connecting port 44 is oil-tightly connected to the joint plug 54 by a sealing function achieved by the combination of the flange portion 54 a and the O-ring 64.

In operation, engine power or motor power is transmitted to a sprocket 30 connected to one end of the drive shaft 5 to thereby rotate the drive shaft 5. As a result, the lubricating oil is sucked into the oil pump 10 from the inlet ports 23, 24, and 25 by the suction forces of the feed pump and the scavenging pump. The lubricating oil supplied into the oil pump 10 is pressurized in the oil pump 10, and then fed under pressure from the outlet ports 21 and 22 to the oil cooler and the lubricated section.

According to this preferred embodiment, the joint plugs 53 and 54 are preliminarily fixed by press fitting to the inlet ports 23 and 24, respectively, to thereby achieve oil tightness without using any sealing members. Thus, unlike the background art, no sealing members are required between the inlet ports 23 and 24 and the joint plugs 53 and 54. Furthermore, the joint plugs 53 and 54 are accurately positioned to the inlet ports 23 and 24 of the oil pump 10 with no play, thereby exhibiting a positioning function. Accordingly, it is unnecessary to use any positioning members such as dowel pins for accurately positioning the oil pump to the connected object.

While the joint plugs 53 and 54 characteristic in the present invention are press-fitted with only the inlet ports 23 and 24 of the oil pump 10 in this preferred embodiment, the present invention is not limited to this preferred embodiment, but the joint plugs according to the present invention may be press-fitted with only the outlet ports 21 and 22 or both the inlet ports 23 and 24 and the outlet ports 21 and 22.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. 

1. A mounting structure of an oil pump for sucking a lubricating oil from an inlet port and feeding said lubricating oil under pressure from an outlet port, said mounting structure comprising: a joint plug for oil-tightly connecting at least one of said inlet port and said outlet port to a connected object, said joint plug having one end portion preliminarily press-fitted with at least one of said inlet port and said outlet port and another end portion adapted to be oil-tightly connected to said connected object by using a sealing member.
 2. The mounting structure of an oil pump according to claim 1, wherein: said oil pump comprises a feed pump and a scavenging pump integrated with each other; and said joint plug comprises a first joint plug press-fitted with an inlet port of said feed pump and a second joint plug press-fitted with an inlet port of said scavenging pump, said first and second joint plugs having seat surfaces at the same level.
 3. The mounting structure of an oil pump according to claim 1, wherein said joint plug has a cylindrical portion and a circular flange portion formed at an axially central position of said cylindrical portion so as to have an outer diameter larger than that of said cylindrical portion, said one end portion of said joint plug being press-fitted until said flange portion abuts against an opening end of at least one of said inlet port and said outlet port.
 4. The mounting structure of an oil pump according to claim 2, wherein said joint plug has a cylindrical portion and a circular flange portion formed at an axially central position of said cylindrical portion so as to have an outer diameter larger than that of said cylindrical portion, said one end portion of said joint plug being press-fitted until said flange portion abuts against an opening end of at least one of said inlet port and said outlet port.
 5. The mounting structure of an oil pump according to claim 3, wherein the other end portion of said joint plug is oil-tightly connected to said connected object through a sealing function obtained by combining said flange portion and an o-ring as said sealing member.
 6. The mounting structure of an oil pump according to claim 4, wherein the other end portion of said joint plug is oil-tightly connected to said connected object through a sealing function obtained by combining said flange portion and an o-ring as said sealing member.
 7. The mounting structure of an oil pump according to claim 1, wherein said at least one of said inlet port and said outlet port has an inner diameter that tapers toward an opening end thereof.
 8. The mounting structure of an oil pump according to claim 1, wherein said sealing member is an o-ring located between said connected object and said another end portion of said joint plug.
 9. A mounting structure for an oil pump, comprising: a joint plug having a first end portion press fitted within at least one of an inlet port and an outlet port of the oil pump, said joint plug having a second end portion connected to a connecting port with a sealing member, the connecting port being in communication with an object to be lubricated.
 10. The mounting structure of an oil pump according to claim 9, wherein: said oil pump comprises a feed pump and a scavenging pump integrated with each other; and said joint plug comprises a first joint plug press-fitted with an inlet port of said feed pump and a second joint plug press-fitted with an inlet port of said scavenging pump, said first and second joint plugs having seat surfaces at the same level.
 11. The mounting structure of an oil pump according to claim 9, wherein said joint plug has a cylindrical portion and a circular flange portion formed at an axially central position of said cylindrical portion so as to have an outer diameter larger than that of said cylindrical portion, said first end portion of said joint plug being press-fitted until said flange portion abuts against an opening end of at least one of said inlet port and said outlet port.
 12. The mounting structure of an oil pump according to claim 10, wherein said joint plug has a cylindrical portion and a circular flange portion formed at an axially central position of said cylindrical portion so as to have an outer diameter larger than that of said cylindrical portion, said first end portion of said joint plug being press-fitted until said flange portion abuts against an opening end of at least one of said inlet port and said outlet port.
 13. The mounting structure of an oil pump according to claim 11, wherein the second end portion of said joint plug is oil-tightly connected to said connecting port through a sealing function obtained by combining said flange portion and an o-ring as said sealing member.
 14. The mounting structure of an oil pump according to claim 12, wherein the second end portion of said joint plug is oil-tightly connected to said connected object through a sealing function obtained by combining said flange portion and an o-ring as said sealing member.
 15. The mounting structure of an oil pump according to claim 9, wherein said at least one of said inlet port and said outlet port has an inner diameter that tapers toward an opening end thereof.
 16. The mounting structure of an oil pump according to claim 9, wherein said sealing member is an o-ring located between said connecting port and said second end portion of said joint plug.
 17. An oil pump, comprising: a feed pump; first and second scavenging pumps integral with the feed pump; a drive shaft rotatably supported within the feed pump and the first and second scavenging pumps; a first joint plug having a first end portion press-fitted within an inlet port of said feed pump and a second joint plug having a first end portion press-fitted within an inlet port of at least one of said first and second scavenging pumps, said first and second joint plugs having seat surfaces at the same level, said first and second joint plugs having second end portions connected to a connecting port with a sealing member, the connecting port being in communication with an object to be lubricated.
 18. The oil pump according to claim 17, wherein said first and second joint plugs have a cylindrical portion and a circular flange portion formed at an axially central position of said cylindrical portion so as to have an outer diameter larger than that of said cylindrical portion, said first end portions of said joint plugs being press-fitted until said flange portions abut against an opening end of said inlet ports of said feed pump and said scavenging pumps.
 19. The oil pump according to claim 17, wherein said inlet ports of said feed pump and said scavenging pumps have an inner diameter that tapers toward an opening end thereof.
 20. The oil pump according to claim 17, wherein said sealing member is an o-ring located between said connecting port and said second end portion of said joint plug. 